D.C. machine, with mechanical and electrical connections among collector segments

ABSTRACT

A small motor having a planar air gap has a rotor comprising a rotor shaft journalled in a carrier pipe of small diameter at whose outer periphery are mounted shape-retaining rotor coils which are cantilevered out into the air gap. This provides a rotor of very small axial moment of inertia, affording very short start-up times. The printed circuit collector has lamella-group connectors on both sides of the substrate. Such a motor is suitable especially for signal-recording or -reproducing apparatus. The arrangement of the rotor coils is symmetrical and yields a very simple and compact motor construction.

This is a continuation of application Ser. No. 522,049 filed Aug. 10,1983, now U.S. Pat. No. 4,568,847.

BACKGROUND OF THE INVENTION

The present invention concerns collector-type D.C. machines, whethermotors or generators, having a multi-pole stator magnet arrangement andan ironless rotor winding comprising a plurality of rotor coils lower innumber than the number of stator poles, the rotor coils being arrangedas a single-layer winding, with the collector of the machine beingcomprising collector lamellas of which predetermined ones areelectrically interconnected by cross-connecting means. Such a machine isdisclosed, for example, in commonly owned Federal Republic of Germanypatent application No. P 32 17 283.4.

SUMMARY OF THE INVENTION

It is the general object of the invention to improve and simplify motorsof such type, as well as their manufacture.

In the preferred embodiment of the invention, the stator has eight polesand the rotor winding six coils, the rotor comprising a collector formedby twelve collector lamellas. Means are provided for transmittingcurrent to and from the collector lamellas and for connecting togetherrespective ones of the lamellas, such means including first and secondbrush arrangements angularly offset from each other by 45+n×90mechanical degrees, wherein n=0, 1, 2 or 3, such means furthermoreincluding cross-connecting means operative for causing the collectorlamellas of a respective collector lamella group to be electricallyconnected together as successive collector lamella groups are engaged bythe first and second brush arrangements, each collector lamella groupconsisting of a respective four collector lamellas spaced one from thenext at angular intervals of 90 mechanical degrees. The six rotor coilsare arranged as three coil-pairs, the two coils of each pair beinglocated diametrically opposite each other and being connected in serieswith each other, the first, second and third coil-pairs being,respectively, electrically connected between collector lamellas of thefirst and second collector lamella groups, between collector lamellas ofthe second and third collector lamella groups, and between collectorlamellas of the third and first collector lamella groups. Preferably,the cross-connecting means comprise first, second and thirdcross-connecting means provided on the rotor arrangement, eachcross-connecting means permanently electrically connecting together thefour collector lamellas of a respective one of the first, second andthird collector lamella groups.

With such a construction one obtains, with a good copper packing factor,a simple manner of production, since only a few connecting operationsare required to establish the few electrical connections to thecollector. This is particularly of advantage in the case of miniaturemotors, such as the present invention preferably concerns; such motorstypically have powers lower than 10 watts. Also, such motor constructionexhibits a symmetrical rotor configuration and, all in all, an extremelycompact structure.

According to a preferred concept of the invention, the constituent rotorcoils of the rotor winding are formed by a single, uninterruptedconductor which is wound without break from one coil to the next,thereby keeping low the number of wires which need be connected to thecollector.

In many cases a low axial moment of inertia of the rotor is desired, forexample in order to assure quick motor start-up. According to a furtherconcept of the invention, the rotor coils are mounted on the rotor attheir radially innermost parts and extend out from there in cantileveredand self-supporting fashion. In this way, the axial moment of theinertia of the rotor is determined substantially exclusively by theinherent weight of the rotor coils themselves. At the same time, therotor coils are surrounded by air on all sides and thus experience aparticularly good cooling action, so that they may be safely subjectedto rather high thermal loading.

The invention furthermore contemplates particularly convenient ways offabricating the collector, but these will be best understood afterdetailed consideration of the collector structures involved.

In addition to the objects and advantages stated above, further objectsand advantages will become apparent from the description of specificembodiments when read in connection with the accompanying Figures.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 schematically depicts a first embodiment of the inventivemachine, here with a flat air gap, an eight-pole stator magnet, a rotorcomprised of six equiangularly arranged rotor coils, and a collectorhaving twelve collector lamellas;

FIG. 2 schematically depicts the collector of FIG. 1, including threecross-connecting means and anti-interference capacitors;

FIG. 3 depicts the rotor winding of FIG. 1, strung out to show themanner in which the six rotor coils can be fabricated using only asingle conductor which proceeds without break from one coil to the next;

FIG. 4 is a longitudinal section through a preferred embodiment of amotor having the rotor-coil and stator-magnet arrangement of FIG. 1,depicted at a greater than true scale;

FIG. 5 is a plan view of the collector of the motor of FIG. 1, seen fromthe brush side, at enlarged scale, with certain parts of the structurebroken away to facilitate visualization;

FIG. 6 is a section, taken alone line VI--VI of FIG. 7, through a springelement which serves to press an anti-interference circuit module intoposition against the collector, and which furthermore serves as across-connecting means interconnecting four collector lamellas;

FIG. 7 is a plan view of the spring element of FIG. 6, seen along lineVII of FIG. 6;

FIG. 8 depicts a collector blank at an earlystage of fabrication of thecollector, seen from the brush side, with an orientation correspondingto that of FIG. 5;

FIG. 9 is a section through the collector blank of FIG. 8, taken alongline IX--IX of FIG. 8, the orientation of the blank being upside-down inFIG. 9 compared to FIG. 8;

FIG. 10 is a view of the collector blank as shown in FIG. 9, in finishedstate, embedded in a molded body of insulating material, ananti-interference circuit module being shown in position in dash-dotlines;

FIG. 11 is a longitudinal section like that of FIG. 4 but of a secondembodiment of an inventive collector-type D.C. machine of symmetricalconstruction, a portion of the structure at the left side being removedto facilitate visualization, the depiction being at about four timestypical true scale;

FIG. 12 is a partially sectioned side view of the carrier member of themotor construction of FIG. 11;

FIG. 13 depicts a molded rotation-transmitting member of the machine ofFIG. 11;

FIG. 14 is an end view of the carrier member of FIG. 12, additionallyshowing, in dash-dot lines, the position of a rotor coil, andfurthermore showing the location of connecting wires;

FIG. 15 depicts the carrier member of FIGS. 12 and 14 with the rotorcoils and collector mounted in place;

FIG. 16 is a view of the structure of FIG. 15 seen from below;

FIG. 17 is a longitudinal section, like that of FIG. 4 or 11, through athird embodiment of an inventive collector-type D.C. machine, on alarger than true scale;

FIG. 18 illustrates in plan view the arrangement of stator magnets andbrushes on the yoke plate of the machine of FIG. 17;

FIG. 19 is a section through an element of the rotor of the machine ofFIGS. 17 and 18, such element serving as a carrier member for the rotorcoils and for the flat collector;

FIG. 20 is a plan view of that face of the element of FIG. 19 on whichthe rotor coils are to be mounted;

FIG. 21 is a plan view of the flat collector of the motor of FIGS.17-21, in incompletely fabricated condition;

FIG. 22 is a plan view of the flat collector of FIG. 21, in finishedcondition; and

FIG. 23 is a plan view of the carrier member of FIG. 19 and, mountedthereon, six equiangularly spaced rotor coils, as well as theconnections of the rotor coils to the collector and to ananti-interference circuit module.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the various Figures identical or corresponding elements are denotedby identical reference numerals. Terms such as "upper", "lower", "left","right", etc., refer to the orientation of a particular structure asdepicted in a particular Figure. To impart a notion of typical truescale, a "1 cm" length designation appears in various Figures, but theexact dimensions of particular depicted structures can of course belarger or smaller.

FIG. 1 is a schematic plan view of a first embodiment of a machine 20according to the invention, in this instance a machine having a flat airgap, FIG. 1 being in particular a view taken along a section planeparallel to the air gap. Depicted are a collector 22 having twelvecollector lamellas 1-12, six rotor coils A-F and, behind the latter, astator magnet 21 which, as shown, has eight poles and is axiallymagnetized. Typically, the stator magnet may be a one-piece annularmember polarized in the illustrated manner, and whose plot of inductionversus angular location along the circumferential direction of thestator magnet has the shape of a trapezoid wave. However, the statormagnet could alternatively be comprised of for example an assembly ofdiscrete magnet segments. The radial extent of the stator magnet ring issuch as to cover the magnetically active sections of the rotor coilsA-F, i.e., the portions of the latter extending generally in a radialdirection. FIG. 1 depicts the stator magnet ring extending radiallyoutward to an exaggerated degree, beyond the radially outer periphery ofthe set of six rotor coils, merely to facilitate visualization of theangular extents of the successive stator poles.

FIG. 2 depicts, in a likewise very schematic manner, the electricalinterconnections as among constituent elements of the collector 22, inthis instance depicted as a generally planar collector; it will beappreciated, however, that other collector geometries could be employed.Of the twelve collector lamellas 1-12, lamellas 4, 8 and 12 are eachprovided with a respective bent-up conductive tab 4A, 8A, 12A. As willbe explained below, the bent-up conductive tabs 4A, 8A, 12A serve aselectrical contacts which form conductive connections to ananti-interference circuit module; the latter comprises three identicallydimensioned capacitors or condensors 23, 24, 25 as shown in FIG. 2.Capacitor 23 is connected between conductive tabs 4A and 8A; capacitor24 between tabs 8A and 12A; capacitor 25 between tabs 12A and 4A.

As shown in FIG. 2, the twelve collector lamellas 1-12 are electricallyinterconnected by three cross-connecting means, as follows:

A first cross-connecting means 26 electrically connects together thefour collector lamellas 2, 5, 8, 11 of a first collector lamella group.

A second cross-connecting means 27 electrically connects together thefour collector lamellas 1, 4, 7, 10 of a second collector lamella group.

A third cross-connecting means 28 electrically connects together thefour collector lamellas 3, 6, 9, 12 of a third collector lamella group.

In the instance depicted in FIG. 2, the set of twelve collector lamellasis thus subdivided into three collector lamella groups, each constitutedby a respective four collector lamallas, the four lamellas of one groupbeing spaced from one another at intervals of 90 mechanical degrees.

Two brushes 30, 31 are employed to transmit current to and fromcollector lamallas 1-12. The brushes 30, 31 are not locateddiametrically opposite each other. Instead, one brush, e.g., brush 30,is mounted on the stator beneath a north pole segment of stator magnet21, and the other brush, i.e., here brush 30, beneath a south polesegment, the angular spacing α between the two brushes being 45+n×90mechanical degrees, wherein n=0, 1, 2 or 3.

It is to be noted that, as an alternative to the rotor-mountedcross-connecting means 26, 27, 28, equivalent cross-connections could beestablished by using, instead of one brush 30 and one brush 31, two setsof brushes, each set of brushes being constituted by four brushes, thefour brushes of one set being angularly offset by about 45 mechanicaldegrees from the four brushes of the other set. In such case, the fourbrushes of one set of brushes would be electrically connected to oneanother, and the four brushes of the other set would be electricallyconnected to one another.

In this first embodiment, the set of six rotor coils A-F is providedwith a total of only three external connection points 32, 33, 34 andthese are, as shown, electrically connected to respective ones of thethree collector lamellas 1, 5, 9. In this respect, reference is made toFIG. 3, which illustrates the manner in which the six coils A-F arefabricated as a continuous-conductor chain of coils. As will be clearfrom a comparison of FIGS. 1 and 3, the six rotor coils A-F areorganized as three coil-pairs A, B; C, D; and E, F. The two coils ofeach coil-pair A, B or C, D or E, F are located diametrically oppositeto each other, relative to the rotor rotation axis.

As shown in FIG. 3, in this embodiment the six rotor coils A-F may bewound from a single conductor which extends without break from one coilto the next. The single conductor, in addition to the portions thereofforming the six coils per se, is comprised of transitional portionswhich extend from one coil to the next. These transitional portions areeither inter-coil transitional portions which extend a distance L₁ fromone coil of a coil-pair to the other coil of the same coil-pair, or elseinter-coil pair transitional portions which extend a distance L₂ from acoil of one coil-pair to a coil of a neighboring coil-pair. As shown,the inter-coil spans L₁ are greater than the inter-coil-pair spans L₂.The ratio L₁ :L₂ can preferably be on the order of 3:2 or 4:3.

As shown in FIG. 3, the inter-coil-pair transitional portions of theconstituent conductor each extend first from a coil of one coil-pair toa respective connection point (at 33 or 34 or 32) and then from suchconnecting point to a coil of an adjoining coil-pair. The connectionpoint 32A, 32F is electrically connected to collector lamella 1.Connecting point 33 is electrically connected to collector lamella 5.Connection point 34 is electrically connected to collector lamella 9. Aswill be appreciated from FIG. 1, each of the six coils A-F issymmetrical with regard to a respective symmetry plane which passesthrough the rotor rotation axis, and the three connection points 32, 33,34 are spatially located near to adjoining coils but angularly offset bya distance d (see FIG. 3) relative to the symmetry plane of therespective coil. As indicated in FIG. 3, all six coils A-F have the samewinding sense.

During assembly of the machine, e.g. the rotor coil A may be secured ata location where its symmetry plane coincides with the radial line ofseparation between collector lamellas 10 and 11, as shown in FIG. 1,with coil B then being located diametrically opposite thereto. Then coilC of FIG. 1 is secured adjoining coil B, with the symmetry plane of coilC coinciding with the line of separation between collector lamellas 2and 3, with coil D being then positioned diametrically opposite coil C.Then coil E is secured in place alongside coil D, with the symmetryplane of coil E coinciding with the line of separation between collectorlamellas 6 and 7, as shown in FIG. 1, and coil F is then secured inplace diametrically opposite to coil E. Electrical connection of theconnecting points 32, 33, 34 to respective collector lamellas hasalready been described.

Naturally, the connection point 32A, instead of being connected tocollector lamellas 1, could equivalently be connected to any of lamellas4, 7 or 10, since the four collector lamellas 1, 4, 7, 10 areelectrically connected together anyway by the second cross-connectingmeans 27. Thus, expressed in another way, in the illustrated embodimentthe coil connecting point 32 is electrically connected to the secondcross-connecting means 27; the coil connection point 33 to the firstcross-connecting means 26, and the connection point 34 to the thirdcross-connecting means 28. Expressed yet another way, the three seriescircuits A-B, C-D, E-F are connected in delta configuration between thethree cross-connecting means 26, 27, 28.

As will be apparent from the above description, the fabrication of thesix rotor coils A-F, by virtue of their formation from a single,uninterrupted, continuously wound conductor, is very simple, andlikewise simple is their assembly and their electrical connection tocollector 22; these are extremely simple and suitable for automatedperformance, especially as only three soldering or welding operationsare required. Due to the offset d of the individual connection points32, 33, 34 there automatically results the correct positioning of thecoil ends relative to the associated collector lamellas.

The individual rotor coils are preferably fabricated with a cementing orbinding lacquer or varnish causing the coils to be inherentlyshape-retaining, so that they may be mounted, as described below, in aself-supporting or cantilevered fashion. Where the aforementionedtransitional portions of the constituent conductor cross the coils, suchlacquer or varnish is absent. For example, the transitional portion 36(FIG. 3) extending from coil B to coil C is not provided with suchlacquer or varnish along segment 37 thereof; the same is true in similarfashion for the other coils. In assembled condition of the machine, thetransitional portions of the rotor coils' constituent conductor arelocated beneath the collector, where they can be securely cemented.

FIG. 4 depicts on a greatly enlarged scale a preferred embodiment of themechanical construction of such a machine, in this instance a drivemotor for the capstan of a signal-recording device for video signals.This device comprises a carrier pipe 40 with a mounting flange 41. Amotor shaft 43 is journalled in roller bearings in carrier pipe 40, onlyone roller bearing unit 42 being illustrated. A carrier member 44 madeof a non-magnetic material, e.g. aluminum, is secured at a hub portion45 thereof to the motor shaft 43. Secured to the underside 46 of carriermember 44, e.g. by means of cement, are the radially inward portions ofthe rotor coils A-F, of which two are illustrated in FIG. 4 and denoted47 and 48, the remaining portions of the rotor coils extending radiallyoutward therefrom in cantilevered fashion. The carrier member 44 can forexample having an external diameter of 4.4 cm, whereas the overallcircular outer periphery of the set of six rotor coils may have adiameter of about 7.8 cm. In this way, the axial moment of inertia isdetermined for the most part only by the six rotor coils themselves.Accordingly, the axial moment of inertia (the so-called GD²) of such arotor 50 is very small and, at the same time, the individual coils 47,48 experience a very effective cooling action and thus can be safelysubjected to high thermal loading.

The rotor coils 47, 48 freely extend radially outward, with theirmagnetically active segments projecting into a flat air gap 53 formedbetween a stator magnet ring 54 and an annular flux-return or yoke plate55 made of iron. As shown in FIG. 1, the stator magnet ring 54 has eightpoles and is axially magnetized. The yoke plate 55 is held in place, bymagnetic attractive force, against the edge of the outer peripheral wall56 of an annular channel-like stator housing 57. The stator housing 57is a deep-drawn sheet-steel part and accommodates in its interior themagnet ring 54, which latter is cemented in place. Stator housing 57 issecured to mounting flange 41 at locations 58, 59 by any appropriateconventional means and, as shown in FIG. 4, has an inner peripheral wall61 which is centered on the carrier pipe 40.

Secured to the bottom face of yoke plate 55 is a molded part 62 made ofelectrically insulating material. Insulating member 62 mounts the twobrushes 30, 31, of which only brush 30 is (in part) visible in thesectional view of FIG. 4. The brush 30 is secured at the base portionthereof to a damping mass 63 which serves to attenuate mechanicaloscillations of the elongated body of the brush. The collector 22 issecured on the hub portion 45 of the carrier member 44. The collector 22comprises a hub member 65 made of electrically insulating material inwhich are embedded the radially inner portions of the collector lamellas1-12. The construction and manner of production of the collector 22 andits embedding hub member 65 will be explained below in greater detail inconjunction with FIGS. 5-10.

In fabricating the collector 22, one commences with a sheet-metal blank66 which has been stamped out to have the configuration depicted in FIG.8. As shown in FIG. 8, at this stage of fabrication the twelve collectorlamellas 1-12 are still all electrically interconnected with oneanother. The first cross-connecting means 26, however, is alreadypresent in the stamped blank of FIG. 8, and as shown electricallyconnects together the collector lamellas 2, 5, 8, 11 at the radiallyinner portions thereof; the first cross-connecting means 26 is alreadyelectrically separated from the other eight collector lamellas by virtueof arcuate cut-outs 67. The bent-up conductive tabs 4A, 8A, 12Aschematically depicted in FIG. 2 are already present on the stamped-outblank of FIG. 8 in bent-up condition (as better seen in FIG. 9,described below). The tabs 4A, 8A, 12A are located radially outward ofthe circular zone swept over by the brushes 30, 31.

FIG. 9 is a section through the stamped-out blank 66 of FIG. 8, takenalong line IX--IX. It is noted that in FIG. 9 the blank 66 is shownupside-down with respect to its depiction in FIG. 8; thus, in FIG. 8 tab4A appears above tab 12A, whereas in FIG. 9 tab 12A appears above tab4A. The orientation of the blank as depicted in FIG. 8 corresponds,however, with the orientation of the blank as viewed in FIG. 5 (yet tobe described).

In the stamped-out blank 66 of FIG. 8, the second cross-connecting means27 is present only in rudimentary form, to the extent of four arcuatecut-outs 68 located radially outward of the operative range of thebrushes. In the circular zone in which the brushes will sweep across thecollector lamellas 1-12, the collector lamellas are, in the stamped-outblank of FIG. 8, already separated one from the next by radial gaps 69.The radial lamella-separating gaps 69 extend radially outward past acircle 72 and, in the region of circle 72, have enlarged portions. Thebent-up conductive tabs 4A, 8A, 12A are likewise located on the circle72.

After fabrication of the collector blank 66 of FIGS. 8 and 9, the blankis embedded in a molded body of synthetic plastic material, preferably apolyamide, the molded body having the form shown in FIG. 10 and, in planview, in FIG. 5. As shown in FIG. 10, such molded body has a central hubportion 65 which completely envelopes the first cross-connecting means26, completely fills the aforementioned arcuate cut-outs 67, andentirely envelopes and embeds the radially inner portions of thecollector lamellas 1-12. In the vicinity of circle 72 (cf. FIGS. 8, 10and 5) the molded insulating member comprises a ring portion 75 which islocated to both axial sides of the collector blank 67 and, in thisvicinity, envelops the collector lamellas from both sides; the materialof ring portion 75 passes through the enlarged portions of the radialgaps 69 (FIG. 8) at the region of circle 72, and likewise passes throughthe circular apertures located intermediate adjoining enlarged portionsof the gaps 69. Spoke-like portions 76 extend integral from the radiallyinner hub portion 65 to the ring portion 75.

After the stamped-out collector blank 66 has been thusly embedded ininsulating material, it is then subjected to a further stampingprocedure, serving to complete the fabrication of the secondcross-connecting means 27, such that the latter be electricallycontinuous only with the collector lamellas 1, 4, 7, 10. One example ofthe way in which this may be accomplsihed can be seen in FIG. 8. Asshown in FIG. 8, further cut-outs 77, 78, 79 may be stamped out toextend the three associated radial gaps 69 out to the associated arcuatecut-out 68. This serves to electrically separate the two collectorlamellas 11, 12 from the second cross-connecting means 27. Three furthersets of such cut-outs 77, 78, 79 are likewise formed, to electricallyseparate the second cross-connecting means 27 from the two collectorlamellas 2, 3, from the two collector lamellas 5, 6, and from the twocollector lamellas 8, 9. When this further stamping-out procedure hasbeen completed, the radially outward zone of the collector blank willnow have the appearance shown in FIG. 5.

The first group of four collector lamellas 2, 5, 8, 11 are continuousonly with the radilly inward first cross-connecting means 26, and thisfirst continuous area from the original blank is shown in FIG. 5 hatchedin by tiny dots.

The second group of four collector lamellas 1, 4, 7, 10 are continuousonly with the radially outward second cross-connecting means 27, andthis second continuous area formed from the original blank is shown inFIG,. 5 hatched in by short fleck-like straight lines.

The third group of four collector lamellas 3, 6, 9, 12 (not hatched inFIG. 5) are, at this stage of fabrication, discontinuous from oneanother and discontinuous from all the remainder of the original blank.The third cross-connecting means 28, which electrically connects thesefour lamellas together, is yet to be provided in a manner describedbelow.

Before that, it is to be noted (FIG. 10) that the three bent-upconductive tabs 4A, 8A, 12A, already described, project axially out ofthe insulating ring portion 75 and are spaced angularly by 120° (FIG.8). The three tabs 4A, 8A, 12A are employed as electrical contacts andelectrically engage three electrical contacts of an annularanti-interference circuit module 82. The annular module 82 may forexample be a cast or molded synthetic plastic body whose interioraccommodates the three anti-interference capacitors 23, 24, 25 of FIG.2. The insulating ring portion 75 is provided with three integralcentering pins 83 which serve to center the annular circuit module 82.The three centering pins 83 are received in recesses in the axial endface of the annular housing of module 82, to positively define theposition of the circuit module. However, the right end face (as viewedin FIG. 10) of the circuit module 82 axially bears only against thethree bent-up contact tabs 4A, 8A, 12A, in order to establish a purelythree-point support against the contact tabs; this assures thatelectrical engagement will be reliably established and maintained withthe three contact tabs.

The annular circuit module 82 is axially pressed against the tabs 4A,8A, 12A by means of a spring member 84 shown mounted in place in FIG. 4,and shown separately in FIGS. 6 and 7. Spring member 84 has a centralannular portion 85 which encircles hub member 65 (FIG. 4). The centralportion 85 bears axially against the anti-interference circuit module82, pressing the latter against the conductive tabs. Extending radiallyoutward from central portion 85 are four identical spoke-like springarms 86, 87, 88, 89 of somewhat Z-shaped configuration. The free ends ofthese four spring arms are planar and extend approximately parallel tothe plane of the central annular portion 85.

This spring member 84 is simultaneously employed as the thirdcross-connecting means 28. As shown in FIG. 5, the planar ends of thefour spring arms 86, 87, 88, 89 are each permanently welded to arespective one of the four collector lamellas 3, 6, 9, 12 of the thirdcollector lamella group, electrically interconnecting them. The weldinglocation is as shown radially outward of the insulating ring portion 75.

As shown in FIG. 5, the connection points 32, 33, 34 for the rotorcoil-pairs are respectively connected, e.g., by soldering, to thecollector lamellas 1, 5, 9, radially outward of the insulating ringportion 75.

From the foregoing description, it will be appreciated that thecollector arrangement depicted in FIG. 5 constitutes an extraordinarilycompact structure whose fabrication can be performed with a remarkablylow number of operations. The span of the coils is as illustratedpreferably greater than 180 electrical degrees. Sector-shaped coils suchas here illustrated are preferred, but circular coils could likewise beemployed.

If it should be desired to replace the three cross-connecting means 26,27, 28 by brushes, then in addition to brush 31 three further suchbrushes must be provided, respectively offset relative thereto by 90°,by 180° and by 270° and all electrically connected to brush 31.Likewise, in addition to brush 30 three further brushes would berequired, likewise offset relative thereto by 90°, 180° and 270° and allelectrically connected to brush 30.

Self-evidently, the collector 22 can have an angular position relativeto the coils A-F other than the one illustrated, provided that thebrushes 30, 31 are likewise shifted by such angle. The spacing d of FIG.3 will then have a different magnitude, and could also be of zeromagnitude.

The illustrated motor has a power consumption of 0.6 W and at 1500 rpmproduces a torque of 0.2 Ncm (20 cmp), and is a miniature motor whichsupplies a torque of very good constancy with a very low axial moment ofinertia.

FIG. 11 depicts, at a scale considerably greater than typical truescale, a second embodiment of the invention, here a drive motor for asignal-recording device for video signals. This device comprises acarrier pipe 140 with a radial mounting flange 141. A motor shaft 143 isjournalled in roller bearings accommodated within the carrier pipe 140,only one roller bearing unit 142 being illustrated. A carrier member 144of non-magnetic material, e.g. aluminum or a suitable synthetic plastic,is secured to the motor shaft 143 at an axial extension 145 of thecarrier member 144. The rotor coils 147, 148 (cf. FIG. 16) are securedat their radially inward portions to a peripheral stepped face of thecarrier member 144 by means of cement; e.g. as illustrated by means of athin fabric layer 151 impregnated with epoxy resin. The carrier member144 can have an outer diameter of e.g. 2.8 cm, whereas the circulararrangement of six rotor coils (cf. FIG. 16) has a general outerperiphery having a diameter of 5.7 cm; i.e., the axial moment of inertiais determined substantially exclusively by the six rotor coils per se,so that the rotor 150 has a very small GD² value, while at the same timethe individual rotor coils 147, 148 experience very good cooling actionand can be safely subjected to high thermal loading.

The coils 147, 148 extend with their magnetically active sections into aflat air gap 153 formed between an upper stator magnet ring 154 and alower stator magnet ring 155. The two stator magnet rings 154, 155 areaxially magnetized and each of eight poles. An annular flux-return oryoke plate 152 made of iron carries magnet ring 155 and is held, bymagnetic holding force, against the rim of the outer peripheral wall 156of a cup-like stator housing 157. Stator housing 157 is a deep-drawnsheet-steel part, and the upper magnet ring 154 accommodated therein iscemented in place. The stator housing is secured by means of screws 158to a flange 141 and, as illustrated, is at its radially inner rim 161centered on the carrier pipe 140.

Secured to the bottom face of yoke plate 152 by means of screws 183 is amolded member 182 made of electrically insulating material and mountingtwo brushes, of which only the brush 130 is visible in FIG. 11. Thescrews 183 extend through apertures 184 in the molded insulating member182. The apertures 184 are, if viewed axially of the motor, of elongatedor arcuate extent, thereby permitting angular shifting of the member 162relative to the rotor axis of the motor, i.e., before tightening ofscrews 183; this makes it possible during assembly to establish anoptimum position for the brushes 130 relative to the stator magnet rings154, 155.

A collector 122 of planar geometry is mounted on the axial extension 145of the carrier member 144. The collector 122 includes a hub member 165made of electrically insulating material which securely embeds theradially inward ends of the collector's twelve collector lamellas. Thecollector 122 may be of the same construction, and fabricated in thesame way, as already described with respect to FIGS. 5-10. Likewise, theeight-pole magnetization of the magnet rings 154, 155 may be the same asalready described with reference to FIG. 1. Also, the arrangement of therotor coils and their electrical connections to one another and to thecollector lamellas may be the same as already described with regard toFIGS. 1-3. As shown in FIG. 16, the rotor coils may here be circular,and fabricated with cementing or binding varnish or lacquer, to impartto the coils shape-retaining properties permitting them to be mounted incantilevered or self-supporting manner; of course, use couldalternatively be made of one or more discrete coil carrier members,although the illustrated cantilevered mounting of the rotor coils ispreferred.

Located above the collector 122 is an annular anti-interference circuitmodule 182 containing three capacitors, whose manner of connection isshown in FIG. 2 as is also the arrangement of collector brushes.

As furthermore shown in FIG. 11, the carrier member 144 has a maximumouter diameter which is smaller by only about 2 mm than the innerdiameter of the magnet ring 155 which encircles it, so that the gap 160between the lower magnet ring 155 and the outer periphery of the carriermember 144 amounts to only about 1-1.5 mm. So small a gap is important,in order that there be provided in the vicinity of the magneticallyactive sections of coils 147, 148 a magnetic field of the greatestpossible homogeneity.

If now the connecting lines for the coils 147, 148 were to be ledthrough this narrow gap 160, then during assembly or later repairs theconnecting lines could easily become wedged in the gap, and thereby bebadly damaged or destroyed. For this reason, as shown in FIGS. 12 and14, the carrier member 144 is of non-circular configuration at its outerperiphery. In particular, the carrier member 144 is of greatest radiusat those locations thereof where a coil 147 is to be secured thereto;between such locations it is of somewhat reduced radius, so that at suchlocations the connecting lines 185 for the collector 122 can be fedthrough and fixed in place by means of cement, or the like, at alocation such as indicated in FIG. 14 at 166.

At its inner periphery 167 the carrier member 144 encircles the carrierpipe 140, forming therewith a long and very narrow gap 168, so thatgrease or oil from the bearings 142 cannot migrate through this narrowgap to the collector 122, and thus not interfere with proper operationof the collector. To this end, the carrier member 144 is provided at itsupper face with a relatively long collar-like extension 169.

The lower axial extension 145 of carrier member 144 is, as shown inFIGS. 11 and 12, provided with two flattened portions 171, 172 whichextend to the inner opening 173 provided for the shaft 143. Shaft 143 islikewise provided with two corresponding flattened portions, of which inFIG. 11 only the flattened portion 174 is visible. A molded part 175(FIG. 13) has an integral opening 176 which is complementary to theseflattened portions. As shown in FIG. 11, molded part 175 is fitted ontothe axial extension 145 and connects the latter with the shaft 143 forjoint rotation therewith. Two dish springs 177 are provided, one bearingagainst a nut 178 screwed onto the lower end of shaft 143, the otherbearing on the axial extension 145; the dish springs accordingly pressthe carrier member 144 upwards against a shoulder 179 on the shaft 143,establishing a definite axial position for the carrier member 144. Thissame construction is employed in the case of the third embodiment, yetto be described.

FIGS. 15 and 16 depict the carrier member 144 when the collector 122 andthe six rotor coils are in assembled and mounted condition. The scale ofthe illustration is here likewise slightly larger than typical truescale. One can appreciate the very compact construction of the rotor 150and its small axial moment of inertia, which makes possible very quickstart-up of the motor in response to energization.

At an operating voltage of 10 V, the illustrated motor has a currentconsumption of 55 mA at 1500 rpm and rated load (i.e., the loadpresented by the driven capstan). The type of motor here involved is aminiature motor exhibiting good efficiency, achieved with very compactconstruction. Tests have shown that such motors can be expected to havea very long service life.

FIGS. 17-23 depict a third embodiment of a D.C. machine according to theinvention, here in the form of a miniature motor 200 which, as shown hasan axial thickness of about 8 mm and a diameter of about 40 mm, and isthus extremely compact. This motor has a current consumption of about180 mA at a D.C. voltage of 10 V at rated power, and at 1500 rpmproduces a torque of about 0.2 Ncm (starting torque 0.95 Ncm). Becauseof its extremely small dimensions, the motor 200 is illustrated at aconsiderably enlarged scale, especially in FIGS. 19-23. To facilitateappreciation of the correspondence between the scale of those Figuresand that of FIGS. 17 and 18, a "1 cm" scale indication is provided forall those Figures. Motor 200 serves for example as the drive motor for avideo-signal signal-recording device. A carrier structure 239 has alongitudinal bore 240 in which are mounted two roller bearings 241, 242for a motor shaft 243. Mounted on the shaft 243, by means of a syntheticplastic hub member 245 (FIG. 19) is a carrier member 244 whichsimultaneously serves for the motor's collector. Carrier member 244 ismade of a glass-fiber-reinforced synthetic plastic, e.g. an epoxy-resin,hard-as-glass web, having a thickness of 1.5 mm and laminated on bothaxial end faces with a thin copper layer of e.g. 17.5 microns, thecollector lamellas and the various requisite conductor paths beingformed by etching away the portions of the copper layer not requiredtherefor, in a manner described below. On the upper face 246 of thecarrier member 244, the individual rotor coils 247, 248 (cf. FIG. 23)are directly secured thereto, at their radially inward portions, bymeans of cement, e.g. by means of an epoxy resin. In this thirdembodiment the rotor coils have, as shown, a diameter of about 13 mm anda thickness of about 2.5 mm. The axial moment of inertia of the rotor isdetermined substantially exclusively by the rotor coils themselves.

The rotor coils 247, 248 are provided with a cementing or bindingvarnish or lacquer imparting shape-retaining properties, and theyproject radially outward in cantilevered fashion into a flat air gap253. Air gap 253 is formed by the upper face of a set of eight roundpermanent magnets 254 of tablet-like shape (having e.g. a diameter ofabout 6 mm) and, as shown in FIG. 18, these magnets 254 are mounted onan annular yoke plate 255 at equal distances from the rotor axis and atequiangular intervals. The permanent magnets 254 are axially magnetizedand have at the sides thereof facing the air gap 253 alternately northand south poles (FIG. 18), forming an eight-pole stator magnetarrangement. The magnets 254 are advantageously samarium-cobalt magnetsof high energy density. This makes it possible to dispense with theupper magnet ring 154 employed in the second embodiment, thereby todecrease the axial length of the motor.

Arranged on the yoke plate 255 are two brushes. Their insulated brushholders 256 are, in space-saving manner, each arranged in a respectiveinterspace between two adjoining permanent magnets 254, the two brushholders 256 being angularly spaced by 135° from each other. The brushholders 256 have a shape mating with the outer peripheries of thepermanent magnets 254, as shown in FIG. 18. The brush springs per se areangled members: Projecting out from each brush holder 256 is a radialspring portion 257 from which at an angle of about 158° thereto thereextends a further portion forming the actual brush 258. The brushes 258are, as illustrated, longitudinally divided and extend tangential to theaperture 260 on the yoke plate 255. The actual contact locations of thebrushes 258, indicated in FIG. 18 by radially extending dash-dot linesat the brush ends, are, in the case of one brush, lined up with asouth-pole magnet 254, and in the case of the other brush lined up witha north-pole magnet 254, these two contact location being spaced by anangular interval of 135°; reference is made to the discussion of angle αin connection with FIG. 2. Yoke plate 255 is provided at its outer rim255 with centering projections 259, of which one can be seen insectional view in FIG. 17. Yoke plate 255 has a central aperture 260through which the free end of shaft 243 projects. This end of shaft 243is provided with an external thread, onto which is screwed a nut 263.Nut 263, through the intermediary of two dish springs 264, presses thehub member 245 upwardly. Hub member 245 has a flattened portion 265(FIG. 19) which engages witha corresponding flattened portion 266 ofshaft 243 (FIG. 17) to prevent hub member 245 from turning relative tothe latter.

A pan-like stator housing 271 is secured by means of screws 270 to thecarrier structure 239. The stator housing 271 is made of magneticallyconductive material and serves as part of the motor's magnetic-fluxcircuit. The flat base of the stator housing 271 has a central aperturewhich is centered on an axial projection 272 of the carrier structure239. The bottom rim of the peripheral wall of stator housing 271 mountsthe yoke plate 255, which latter is held against such rim by the forceof magnetic attraction, the marginal projections 259 of yoke plate 255serving to center the latter with respect to the rim of stator housing271.

The air gap 253 is accordingly formed between the permanent magnets 254on the one hand and on the other hand the flat base of the pan-likestator housing 271. The brushes 258 are each provided with a lead 273which exits the motor downwardly from out the yoke plate 255.

FIGS. 21 and 22 illustrate the fabrication of the collector on the loweraxial face 230 of the carrier member 244. As shown in FIG. 21, twelvecollector lamellas 201-212 are formed by etching away those portions ofa copper coating not needed therefor, the copper coating being providedon a plate 244', plate 244' later being cut to form carrier member 244.In similar fashion there is formed a radially outer cross-connectingmeans 228 which electrically connects together the four collectorlamellas 203, 206, 209, 212, in correspondence to cross-connecting means28 of FIG. 2. Likewise, by removing the portions of the copper coatingnot needed therefor, there is formed a radially inner cross-connectingmeans 226 which electrically connects together the four collectorlamellas 202, 205, 208, 211, in correspondence to cross-connecting means26 of FIG. 2. Lastly, on the reverse face of the plate 244',corresponding to the bottom face 230 of carrier member 244, there isformed as shown in FIG. 20 yet another such cross-connecting means 227which electrically connects together the collector lamellas 201, 204,207, 210, corresponding to the cross-connecting means 27 of FIG. 2.Also, as shown in FIG. 21, for purposes of fabrication, there isadditionally formed a conductive path 229 connecting together thecollector lamellas 210, 211 and 212, and located radially outward of thecross-connecting means 228.

The plate 244' is furthermore provided with six through-conductivecircuit holes 231-236 which electrically connect together conductiveregions located on opposite faces of the plate 244'. The mechanicalapertures of the circuit holes are provided on their inner peripheralwalls with a layer of deposited copper, which is continuous with thecopper layer surrounding each circuit hole at both faces of the plate244'. Circuit hole 231 electrically connects lamella 207 with thecross-connecting conductor path 227 and with a soldering land 214 towhich the rotor winding 247, 248 will be connected. Circuit hole 232electrically connects collector lamella 204 with the cross-connectingconductor path 227. Circuit hole 233 electrically connects collectorlamella 203 as well as the cross-connecting conductor path 228 to asoldering land 215 to which the rotor winding 247, 248 is to beconnected. Circuit hole 234 electrically connects collector lamella 201to the cross-connecting conductor path 227. Circuit hole 235electrically connects collector lamella 211 and the cross-connectingconductor path 226 to the soldering land 216 to which the rotor winding247, 248 is to be connected. Circuit hole 236 electrically connectscollector lamella 210 to the cross-connecting conductor path 227.

After production of the circuit holes 231-236 and the electricalthrough-conductive connections thereof, which conductively connecttogether the conductive zones surrounding each circuit hole at the twoopposite faces of plate 244', i.e., in the state shown in FIG. 21, allconductor paths and lamellas on both faces of the plate 244' are thusnow electrically interconnected as required in the final assembly. Withthe collector plate 244' in this state, firstly the thickness of thesemetallic components is approximately tripled by galvanic deposition ofcopper. Then a thin layer of nickel is galvanically deposited atop thecopper layer, especially on that side 230 of the plate 244' where thebrushes 257, 258 are situated. Thereafter, on that side is galvanicallydeposited atop the nickel layer a hard gold coating, having a thicknessof a few microns, and forming the surface of the collector upon whichthe brushes actually ride. Finally, the carrier member 244 (see FIG. 22)is stamped out from the preliminary plate 244' and provided with acentral aperture 276, into which the hub member 245 (see FIG. 20) isthen provided, e.g. by an injection-molding process. As a consequence ofsuch stamping out of the final carrier member 244, the conductor path229, needed for the aforementioned galvanic deposition steps, isremoved, and the three cross-connecting conductor paths 226, 227, 228become electrically discontinuous from one another.

FIG. 23 depicts the carrier member 244 with six rotor coils securedthereto at its upper face 246. These coils, denoted 247 and 248 in FIG.17, are in FIG. 23 denoted A'-E' in correspondence to the description ofFIGS. 1 and 3. Starting clockwise from the 1-o'clock position in FIG.23, the sequence of rotor coils is E', D', A', F', C', B'. Thesecircular coils A'-E' are, in exactly the same way as in FIG. 3,constituted by a single, uninterrupted conductor and provided withsimilar connection points for connection to collector lamella groups.The connections between individual coils are expressly depicted in FIG.23, as is the winding sense of the coils.

Specifically:

The coils A' and B' are connected in series with each other between thesoldering lands 216 and 214, i.e., between the cross-connectingconductor paths 226 and 227.

The coils C' and D' are connected in series with each other between thesoldering lands 216 and 215, i.e., between the cross-connectingconductor paths 226 and 228.

The coils E' and F' are connected in series with each other between thesoldering lands 215 and 214, i.e. between the cross-connecting conductorpaths 228 and 227.

Further provided is a capacitor module 280 accommodating threedelta-connected capacitors which serve to suppress interference effects.Module 280 is electrically insulating at its underface, at which face itis secured to the carrier member 244, e.g., by cementing. The upper faceof module 280 is provided with three soldering lands, to which, asillustrated, the three connecting points from the three delta-connectedcoil-pairs A'-B', C'-D', E'-F' are respectively soldered. For example,the connection point 281 between the coils B' and C' extends out to thesoldering land 216, soldered thereto, and from there furthermore extendsto the top one of the three soldering lands on the upper face ofcapacitor module 280, being soldered to the top land. The two otherconnection points are analogously connected, and their connectionsexpressly shown in FIG. 23. The circuit depiction of the connection ofthe three capacitors to the rotor coils and the collector lamellas isthe same as in FIG. 2.

The motor of this third embodiment constitutes a particularly smallvariant of the invention, especially suitable for use in battery-poweredvideo recorders, for which application low motor weight is of specialimportance. Self-evidently, however, the motor of the third embodimentis not limited to such application, nor to the stated dimensions,voltages, etc. In comparison to the motor of the first embodiment, thatof the third embodiment has a somewhat inferior efficiency; however, itsdimensions are a fraction of those of the motor of the first embodimentand its power about the same. It will be apparent that the form ofconstruction exhibited by the third embodiment is equally applicable tomotors where the number of rotor coils, stator poles and/or collectorlamellas differs from those illustrated herein, merely for example asshown in Federal Republic of Germany Offenlegungsschrift No. DE-OS 32 17283, the disclosure of which is incorporated herein by reference. Thus,the structural features exhibited in this third disclosed embodiment ofthe present invention are to be considered of inventive significance perse.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions and fabrication procedures differing from the typesdescribed above.

While the invention has been illustrated and described as embodied inflat-air-gap motors having stated numbers of stator poles, rotor coilsand collector lamellas, as well as procedures for their fabrication, itis not intended to be limited to the details shown, since variousmodifications and structural changes may be made without departing inany way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

I claim:
 1. A direct-current machine comprisinga stator including astator magnet arrangement including a circumferential succession ofstator poles; a multi-coil ironless rotor arrangement mounted forrotation about a rotor axis, and including a plurality of coils arrangedin a single winding layer at equiangular intervals about the rotor axis,the rotor arrangement furthermore including a collector arrangementhaving a circumferential succession of collector lamellas arrangedequiangularly in a circle about the rotor axis, the plurality ofcollector lamellas consisting of a plurality of collector lamellagroups, the collector lamella groups each having the same number ofcollector lamellas, the individual collector lamellas of an individualcollector lamella group being angularly spaced from one another inaccordance with a predetermined scheme of angular spacing, saidpredetermined scheme of angular spacing being the same for theindividual collector lamellas of each individual one of the collectorlamella groups, means for transmitting current to and from the collectorlamellas and for electrically connecting together respective collectorlamellas, said means including a plurality of angularly spaced brusharrangements on the stator electrically engaging predeterminedrespective collector lamellas in respective different angular positionsof the rotor arrangement relative to the stator, saidcurrent-transmitting means furthermore including a plurality ofcross-connecting means operative for causing the collector lamellas ofrespective collector lamella groups to be electrically connectedtogether as successive collector lamella groups are electrically engagedby the plurality of angularly spaced brush arrangements, the pluralityof cross-connecting means being provide on the rotor arrangement, witheach of the cross-connecting means electrically connecting together inpermanent fashion the collector lamellas of the respective one of saidplurality of collector lamella groups, one of said cross-connectingmeans and the collector lamellas connected by the latter beingrespective parts of a one-piece body of electrically conductivematerial.
 2. A direct-current machine comprisinga stator including astator magnet arrangement including a circumferential succession ofstator poles; a multi-coil ironless rotor arrangement mounted forrotation about a rotor axis, and including a plurality of coils arrangedin a single winding layer at equiangular intervals about the rotor axis,the rotor arrangement furthermore including a collector arrangementhaving a circumferential succession of collector lamellas arrangedequiangularly in a circle about the rotor axis, the plurality ofcollector lamellas consisting of a plurality of collector lamellagroups, the collector lamella groups each having the same number ofcollector lamellas, the individual collector lamellas of an individualcollector lamella group being angularly spaced from one another inaccordance with a predetermined scheme of angular spacing, saidpredetermined scheme of angular spacing being the same for theindividual collector lamellas of each individual one of the collectorlamella groups, means for transmitting current to and from the collectorlamellas and for electrically connecting together respective collectorlamellas, said means including a plurality of angularly spaced brusharrangements on the stator electrically engaging predeterminedrespective collector lamellas in respective different angular positionsof the rotor arrrangement relative to the stator, saidcurrent-transmitting means furthermore including a plurality ofcross-connecting means operative for causing the collector lamellas ofrespective collector lamella groups to be electrically connectedtogether as successive collector lamella groups are electrically engagedby the plurality of angularly spaced brush arrangements, the pluralityof cross-connecting means being provided on the rotor arrangement, witheach of the cross-connecting means electrically connecting together inpermanent fashion the collector lamellas of the respective one of saidplurality of collector lamella groups, one of said cross-connectingmeans being spatially located to one respective side of saidcircumferential succession of collector lamellas, another of saidcross-connecting means being spatially located to an opposite respectiveside of said circumferential succession of collector lamellas.
 3. Adirect-current machine as defined in claim 2, said one of saidcross-connecting means and the associated collector lamellaselectrically connected thereby being respective parts of a one-piecebody of electrically conductive material, said other of saidcross-connecting means and the associated collector lamellaselectrically connected thereby being respective parts of anotherone-piece body of electrically conductive material.
 4. A direct-currentmachine comprisinga stator including a stator magnet arrangementincluding a circumferential succession of stator poles; a multi-coilironless rotor arrangement mounted for rotation about a rotor axis, andincluding a plurality of coils arranged in a single winding layer atequiangular intervals about the rotor axis, the rotor arrangementfurthermore including a collector arrangement having a circumferentialsuccession of collector lamellas arranged equiangularly in a circleabout the rotor axis, the plurality of collector lamellas consisting ofa plurality of collector lamella groups, the collector lamella groupseach having the same number of collector lamellas, the individualcollector lamellas of an individual collector lamella group beingangularly spaced from one another in accordance with a predeterminedscheme of angular spacing, said predetermined scheme of angular spacingbeing the same for the individual collector lamellas of each individualone of the collector lamella groups, means for transmitting current toand from the collector lamellas and for electrically connecting togetherrespective collector lamellas, said means including a plurality ofangularly spaced brush arrangements on the stator electrically engagingpredetermined respective collector lamellas in respective differentangular positions of the rotor arrangement relative to the stator, saidcurrent-transmitting means furthermore including a plurality ofcross-connecting means operative for causing the collector lamellas ofrespective collector lamella groups to be electrically connectedtogether as successive collector lamella groups are electrically engagedby the plurality of angularly spaced brush arrangements, the pluralityof cross-connecting means being provided on the rotor arrangement, witheach of the cross-connecting means electrically connecting together inpermanent fashion the collector lamellas of the respective one of saidplurality of collector lamella groups, one of said cross-connectingmeans being spatially located to one side of said circumferentialsuccession of collector lamellas, said collector arrangement beinggenerally planar and including a mounting hub of electrically insulatingmaterial for mounting the collector arrangement on the rotorarrangement, said one of said cross-connecting means being at least inpart located within the mounting hub.
 5. A direct-current machinecomprisinga stator including a stator magnet arrangement including acircumferential succession of stator poles; a multi-coil ironless rotorarrangement mounted for rotation about a rotor axis, and including aplurality of coils arranged in a single winding layer at equiangularintervals about the rotor axis, the rotor arrangement furthermoreincluding a collector arrangement having a circumferential succession ofcollector lamellas arranged equiangularly in a circle about the rotoraxis, the plurality of collector lamellas consisting of a plurality ofcollector lamella groups, the collector lamella groups each having thesame number of collector lamellas, the individual collector lamellas ofan individual collector lamella group being angularly spaced from oneanother in accordance with a predetermined scheme of angular spacing,said predetermined scheme of angular spacing being the same for theindividual collector lamellas of each individual one of the collectorlamella groups, means for transmitting current to and from the collectorlamellas and for electrically connecting together respective collectorlamellas, said means including a plurality of angularly spaced brusharrangements on the stator electrically engaging predeterminedrespective collector lamellas in respective different angular positionsof the rotor arrangement relative to the stator, saidcurrent-transmitting means furthermore including a plurality ofcross-connecting means operative for causing the collector lamellas ofrespective collector lamella groups to be electrically connectedtogether as successive collector lamella groups are electrically engagedby the plurality of angularly spaced brush arrangements, the pluralityof cross-connecting means being provided on the rotor arrangement, witheach of the cross-connecting means electrically connecting together inpermanent fashion the collector lamellas of the respective one of saidplurality of collector lamella groups, said collector arrangement beinggenerally planar, said plurality of cross-connecting means being formedby respective portions of electrically conductive material provided onsaid generally planar collector arrangement, the electrically conductivematerial of more than one of said plurality of cross-connecting meansincluding, for each of said more than one of said plurality ofcross-connecting means, at least one respective contact portionprojecting out from the general plane of the collector arrangement, saidrotor arrangement furthermore including an anti-interference circuitmodule containing anti-interference circuit components, theanti-interference circuit module being electrically engaged by saidcontact portions.
 6. A direct-current machine as defined in claim 5, oneof said plurality of cross-connecting means including a discreteelectrically conductive member electrically connected to the lamellas ofa respective collector lamella group and so shaped as to form a springmember which keeps said anti-interference module in a positionelectrically engaged by said contact portions.
 7. A direct-currentmachine as defined in claim 6, said discrete electrically conductivemember being of a shape including a plurality of equiangularly spacedspoke-like portions each of which is in direct electrical engagementwith a respective one of the collector lamellas of a respectivecollector lamella group.
 8. A direct-current machine comprisinga statorincluding a stator magnet arrangement including a circumferentialsuccession of stator poles; a multi-coil ironless rotor arrangementmounted for rotation about a rotor axis, and including a plurality ofcoils arranged in a single winding layer at equiangular intervals aboutthe rotor axis, the rotor arrangement furthermore including a collectorarrangement having a circumferential succession of collector lamellasarranged equiangularly in a circle about the rotor axis, the pluralityof collector lamellas consisting of a plurality of collector lamellagroups, the collector lamella groups each having the same number ofcollector lamellas, the individual collector lamellas of an individualcollector lamella group being angularly spaced from one another inaccordance with a predetermined scheme of angular spacing, saidpredetermined scheme of angular spacing being the same for theindividual collector lamellas of each individual one of the collectorlamella groups, means for transmitting current to and from the collectorlamellas and for electrically connecting together respective collectorlamellas, said means including a plurality of angularly spaced brusharrangements on the stator electrically engaging predeterminedrespective collector lamellas in respective different angular positionsof the rotor arrangement relative to the stator, saidcurrent-transmitting means furthermore including a plurality ofcross-connecting means operative for causing the collector lamellas ofrespective collector lamella groups to be electrically connectedtogether as successive collector lamella groups are electrically engagedby the plurality of angularly spaced brush arrangements, the pluralityof cross-connecting means being provided on the rotor arrangement, witheach of the cross-connecting means electrically connecting together inpermanent fashion the collector lamellas of the respective one of saidplurality of collector lamella groups, the collector arrangement beinggenerally planar and comprising a substrate of electrically insulatingmaterial and thereon a partly etched away thin metallic layer whoseremaining portions include portions which form said collector lamellasand at least one of said cross-connecting means.
 9. A direct-currentmachine comprisinga stator including a stator magnet arrangementincluding a circumferential succession of stator poles; a multi-coilironless rotor arrangement mounted for rotation about a rotor axis, andincluding a plurality of coils arranged in a single winding layer atequiangular intervals about the rotor axis, the rotor arrangementfurthermore including a collector arrangement having a circumferentialsuccession of collector lamellas arranged equiangularly in a circleabout the rotor axis, the plurality of collector lamellas consisting ofa plurality of collector lamella groups, the collector lamella groupseach having the same number of collector lamellas, the individualcollector lamellas of an individual collector lamella group beingangularly spaced from one another in accordance with a predeterminedscheme of angular spacing, said predetermined scheme of angular spacingbeing the same for the individual collector lamellas of each individualone of the collector lamella groups, means for transmitting current toand from the collector lamellas and for electrically connecting togetherrespective collector lamellas, said means including a plurality ofangularly spaced brush arrangements on the stator electrically engagingpredetermined respective collector lamellas in respective differentangular positions of the rotor arrangement relative to the stator, saidcurrent-transmitting means furthermore including a plurality ofcross-connecting means operative for causing the collector lamellas ofrespective collector lamella groups to be electrically connectedtogether as successive collector lamella groups are electrically engagedby the plurality of angularly spaced brush arrangements, the pluralityof cross-connecting means being provided on the rotor arrangement, witheach of the cross-connecting means electrically connecting together inpermanent fashion the collector lamellas of the respective one of saidplurality of collector lamella groups, the collector arrangement beinggenerally planar and comprising a substrate of electrically insulatingmaterial having two major faces and on one face a partly etched awaythin metallic layer whose remaining portions include portions which formsaid collector lamellas and on its other face a partly etched away thinmetallic layer whose remaining portions include portions which form oneof said cross-connecting means, the portions of the thin metallic layerswhich form said one of said cross-connecting means and the collectorlamellas to which said one of said cross-connecting means iselectrically connected including registering through-conductive circuitholes on the two faces of the substrate.
 10. A direct-current machinecomprisinga stator including a stator magnet arrangement including acircumferential succession of stator poles; a multi-coil ironless rotorarrangement mounted for rotation about a rotor axis, and including aplurality of coils arranged in a single winding layer at equiangularintervals about the rotor axis, the rotor arrangement furthermoreincluding a collector arrangement having a circumferential succession ofcollector lamellas arranged equiangularly in a circle about the rotoraxis, the plurality of collector lamellas consisting of a plurality ofcollector lamella groups, the collector lamella groups each having thesame number of collector lamellas, the individual collector lamellas ofan individual collector lamella group being angularly spaced from oneanother in accordance with a predetermined scheme of angular spacing,said predetermined scheme of angular spacing being the same for theindividual collector lamellas of each individual one of the collectorlamella groups, means for transmitting current to and from the collectorlamellas and for electrically connecting together respective collectorlamellas, said means including a plurality of angularly spaced brusharrangements on the stator electrically engaging predeterminedrespective collector lamellas in respective different angular positionsof the rotor arrangement relative to the stator, saidcurrent-transmitting means furthermore including a plurality ofcross-connecting means operative for causing the collector lamellas ofrespective collector lamella groups to be electrically connectedtogether as successive collector lamella groups are electrically engagedby the plurality of angularly spaced brush arrangements, the pluralityof cross-connecting means being provided on the rotor arrangement, witheach of the cross-connecting means electrically connecting together inpermanent fashion the collector lamellas of the respective one of saidplurality of collector lamella groups, the collector arrangement beinggenerally planar and comprising a substrate of electrically insulatingmaterial having two major faces and on one face a partly etched awaythin metallic layer whose remaining portions include portions which formsaid collector lamellas and on its other face a partly etched away thinmetallic layer whose remaining portions include portions which formconductive connecting portions electrically connected to the collectorlamellas on said one face of the substrate, the plurality of coils beingelectrically connected to the conductive connecting portions on saidother face of the substrate and thereby being electrically connected tothe collector lamellas on said one face of the substrate.
 11. Adirect-current machine comprisinga stator including a stator magnetarrangement including a circumferential succession of stator poles; amulti-coil ironless rotor arrangement mounted for rotation about a rotoraxis, and including a plurality of coils arranged in a single windinglayer at equiangular intervals about the rotor axis, the rotorarrangement furthermore including a collector arrangement having acircumferential succession of collector lamellas arranged equiangularlyin a circle about the rotor axis, the plurality of collector lamellasconsisting of a plurality of collector lamella groups, the collectorlamella groups each having the same number of collector lamellas, theindividual collector lamellas of an individual collector lamella groupbeing angularly spaced from one another in accordance with apredetermined scheme of angular spacing, said predetermined scheme ofangular spacing being the same for the individual collector lamellas ofeach individual one of the collector lamella groups, means fortransmitting current to and from the collector lamellas and forelectrically connecting together respective collector lamellas, saidmeans including a plurality of angularly spaced brush arrangementsprovided on the stator electrically engaging predetermined respectivecollector lamellas in respective different angular positions of therotor arrangement relative to the stator, said current-transmittingmeans furthermore including a plurality of cross-connecting meansoperative for causing the collector lamellas of respective collectorlamella groups to be electrically connected together as successivecollector lamella groups are electrically engaged by the plurality ofangularly spaced brush arrangements, the collector arrangement beinggenerally planar and comprising a substrate of electrically insulatingmaterial having two major faces and on one face a partly etched awaythin metallic layer whose remaining portions include portions which formsaid collector lamellas and on its other face a partly etched away thinmetallic layer whose remaining portions include portions which formconductive connecting portions electrically connected to the collectorlamellas on said one face of the substrate, the plurality of coils beingelectrically connected to the conductive connecting portions on saidother face of the substrate and thereby being electrically connected tothe collector lamellas on said one face of the substrate.
 12. Adirect-current machine as defined in claim 11, said plurality of coilsbeing furthermore mechanically mounted on said other face of thesubstrate.
 13. A direct-current machine as defined in claim 1, saidcoils being constituted by conductor means wound without interruptionfrom one coil to the next.
 14. A direct-current machine as defined inclaim 2, said coils being constituted by conductor means wound withoutinterruption from one coil to the next.
 15. A direct-current machine asdefined in claim 3, said coils being constituted by conductor meanswound without interruption from one coil to the next.
 16. Adirect-current machine as defined in claim 4, said coils beingconstituted by conductor means wound without interruption from one coilto the next.
 17. A direct-current machine as defined in claim 5, saidcoils being constituted by conductor means wound without interruptionfrom one coil to the next.
 18. A direct-current machine as defined inclaim 6, said coils being constituted by conductor means wound withoutinterruption from one coil to the next.
 19. A direct-current machine asdefined in claim 7, said coils being constituted by conductor meanswound without interruption from one coil to the next.
 20. Adirect-current machine as defined in claim 8, said coils beingconstituted by conductor means wound without interruption from one coilto the next.
 21. A direct-current machine as defined in claim 9, saidcoils being constituted by conductor means wound without interruptionfrom one coil to the next.
 22. A direct-current machine as defined inclaim 10, said coils being constituted by conductor means wound withoutinterruption from one coil to the next.
 23. A direct-current machine asdefined in claim 11, said coils being constituted by conductor meanswound without interruption from one coil to the next.
 24. Adirect-current machine as defined in claim 12, said coils beingconstituted by conductor means wound without interruption from one coilto the next.